linux-toradex.git/drivers/usb/host/ehci-timer.c, branch v3.10.78

USB: EHCI: improve end_unlink_async()

2013-03-25T20:36:32+00:00

This patch (as1665) changes the way ehci-hcd's end_unlink_async()
routine works in order to avoid recursive execution and to be more
efficient:

	Now when an IAA cycle ends, a new one gets started up right
	away (if it is needed) instead of waiting until the
	just-unlinked QH has been processed.

	The async_iaa list is renamed to async_idle, which better
	expresses its new purpose: It is now the list of QHs which are
	now completely idle and are waiting to be processed by
	end_unlink_async().

	A new flag is added to track whether an IAA cycle is in
	progress, because the list formerly known as async_iaa no
	longer stores the QHs waiting for the IAA to finish.

	The decision about how many QHs to process when an IAA cycle
	ends is now made at the end of the cycle, when we know the
	current state of the hardware, rather than at the beginning.
	This means a bunch of logic got moved from start_iaa_cycle()
	to end_unlink_async().

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

USB: EHCI: convert singly-linked lists to list_heads

2013-03-25T20:35:05+00:00

This patch (as1664) converts ehci-hcd's async_unlink, async_iaa, and
intr_unlink from singly-linked lists to standard doubly-linked
list_heads.  Originally it didn't seem necessary to use list_heads,
because items are always added to and removed from these lists in FIFO
order.  But now with more list processing going on, it's easier to use
the standard routines than continue with a roll-your-own approach.

I don't know if the code ends up being notably shorter, but the
patterns will be more familiar to any kernel hacker.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

USB: EHCI: fix up incorrect merge resolution

2013-03-21T22:00:18+00:00

This patch (as1671) fixes up an incorrect resolution of a merge
conflict between Greg KH's usb-linus branch and his usb-next branch.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

Merge branch 'usb-linus' into usb-next

2013-03-20T23:21:47+00:00

This is to pick up the fixes in that branch, and let Alan fix the merge
error in drivers/usb/host/ehci-timer.c better than I just did (as I know
I messed it up...)

Signed-off-by: Greg Kroah-Hartman

USB: EHCI: fix regression in QH unlinking

2013-03-20T23:17:22+00:00

This patch (as1670) fixes a regression caused by commit
6402c796d3b4205d3d7296157956c5100a05d7d6 (USB: EHCI: work around
silicon bug in Intel's EHCI controllers).  The workaround goes through
two IAA cycles for each QH being unlinked.  During the first cycle,
the QH is not added to the async_iaa list (because it isn't fully gone
from the hardware yet), which means that list will be empty.

Unfortunately, I forgot to update the IAA watchdog timer routine.  It
thinks that an empty async_iaa list means the timer expiration was an
error, which isn't true any more.  This problem didn't show up during
initial testing because the controllers being tested all had working
IAA interrupts.  But not all controllers do, and when the watchdog
timer expires, the empty-list check prevents the second IAA cycle from
starting.  As a result, URB unlinks never complete.  The check needs
to be removed.

Among the symptoms of the regression are processes stuck in D wait
states and hangs during system shutdown.

Signed-off-by: Alan Stern 
Reported-and-tested-by: Stephen Warren 
Reported-and-tested-by: Sven Joachim 
Reported-by: Andreas Bombe 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

USB: EHCI: reorganize ehci_iaa_watchdog()

2013-03-18T23:05:58+00:00

This patch (as1635) rearranges the control-flow logic in
ehci_iaa_watchdog() slightly to agree better with the comments.  It
also changes a verbose-debug message to a regular debug message.
Expiration of the IAA watchdog is an unusual event and can lead to
problems; we need to know about it if it happens during debugging.  It
should not be necessary to set a "verbose" compilation option.

No behavioral changes other than the debug message.  Lots of apparent
changes to the source text, though, because the indentation level was
decreased.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

USB: EHCI: decrease schedule-status poll timeout

2013-03-18T23:05:58+00:00

This patch (as1657) decreases the timeout used by ehci-hcd for polling
the async and periodic schedule statuses.  The timeout is currently
set to 20 ms, which is much too high.  Controllers should always
update the schedule status within one or two ms of being told to do
so; if they don't then something is wrong.

Furthermore, bug reports have shown that sometimes controllers
(particularly those made by VIA) don't update the status bit at all,
even when the schedule does change state.  When this happens, polling
for 20 ms would cause an unnecessarily long delay.

The delay is reduced to somewhere between 2 and 4 ms, depending on the
slop allowed by the kernel's high-res timers.

Signed-off-by: Alan Stern 
Signed-off-by: Greg Kroah-Hartman

USB: EHCI: revert "remove ASS/PSS polling timeout"

2013-02-26T21:22:38+00:00

This patch (as1649) reverts commit
55bcdce8a8228223ec4d17d8ded8134ed265d2c5 (USB: EHCI: remove ASS/PSS
polling timeout).  That commit was written under the assumption that
some controllers may take a very long time to turn off their async and
periodic schedules.  It now appears that in fact the schedules do get
turned off reasonably quickly, but some controllers occasionally leave
the schedules' status bits turned on and consequently ehci-hcd can't
tell that the schedules are off.

VIA controllers in particular have this problem.  ehci-hcd tells the
hardware to turn off the async schedule, the schedule does get turned
off, but the status bit remains on.  Since the EHCI spec requires that
the schedules not be re-enabled until the previous disable has taken
effect, with an unlimited timeout the async schedule never gets turned
back on.  The resulting symptom is that the system is unable to
communicate with USB devices.

Signed-off-by: Alan Stern 
Reported-and-tested-by: Ronald 
Reported-and-tested-by: Paul Hartman 
Reported-and-tested-by: Dieter Nützel 
Reported-and-tested-by: Jean Delvare 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

USB: EHCI: remove ASS/PSS polling timeout

2013-01-25T21:58:20+00:00

This patch (as1647) attempts to work around a problem that seems to
affect some nVidia EHCI controllers.  They sometimes take a very long
time to turn off their async or periodic schedules.  I don't know if
this is a result of other problems, but in any case it seems wise not
to depend on schedule enables or disables taking effect in any
specific length of time.

The patch removes the existing 20-ms timeout for enabling and
disabling the schedules.  The driver will now continue to poll the
schedule state at 1-ms intervals until the controller finally decides
to obey the most recent command issued by the driver.  Just in case
this hides a problem, a debugging message will be logged if the
controller takes longer than 20 polls.

I don't know if this will actually fix anything, but it can't hurt.

Signed-off-by: Alan Stern 
Tested-by: Piergiorgio Sartor 
CC: 
Signed-off-by: Greg Kroah-Hartman

USB: EHCI: convert warning messages to debug-level

2012-09-21T16:37:53+00:00

This patch (as1606) converts two warning messages in the ehci-hcd
driver to debug messages, and adds a little extra information to each.

The log messages occur when an EHCI controller takes too long (more
than 20 ms) to turn its async or periodic schedule on or off.  If this
happens at all, it's liable to happen quite often and there's no point
spamming the system log with these warnings.  Furthermore, there's
nothing much we can do about it when the problem happens.

Signed-off-by: Alan Stern 
Reported-and-tested-by: Thomas Voegtle 
Cc: stable  # [3.6]
Signed-off-by: Greg Kroah-Hartman